 
 (defn collection-updated
   [item]
+  {:pre [(us/valid? ::collection-entity item)]}
   (CollectionUpdated. item))
 
 ;; --- Update Collection


(defn collection-created
  [item]
  (CollectionCreated. item))

;; --- Create Collection

                   ::mimetype
                   ::thumbnail
                   ::url
                   ::version
                   ::collection
                   ::user]))

